While my boat sleeps through most of the winter, I would like to apply a battery tender to maintain the batteries. Would any of you have a recommendation for a battery tender? I have 110 power available on my dock/hoist. Thanks.

Battery Tender is a Brand namehttp://batterytender.com/
They work great, 2 Kinds of Battery chargers, The kind you mount in your boat, like The the ProMariner ProSport 20 talked about above, and the Battery tender you talked about that is made to sit in and around and then you unplug it and go on your way. They are cheaper and work well. Depending on what kind of batterys you have, Example im not sure the Battery tender is a SMART charger that has difrent program cycles for diffrent types of batterys.
If you have a traditional Wet/cell battery a battery tender will do the trick. If you have AGM batterys like a Optima I would go for a more expencieve smart charger

Thanks Grant. Since I want to simply keep my fully charged batteries healthy while the boat sits for a month or two between outings, I am thinking the Battery Tender JR will do the job. Yes, I have standard lead acid batteries but I have a pair of them. Any advice on how to maintain the pair of batteries? Can I wire the tender to the perko and have the perko set to "both" to have both batteries tended?

Dane yes if you directley to the battery's the battery tender comes with a quick disconnect you can buy Battey tenders that will charge more than one battery at a time. If you have anything else that could use a Battey tender u can get more quick disconnects and use it for other battery's while ur boat is in use all summer

One "Smart" battery tender cannot charge 2 batteries at once while the perko is set on "both". It needs to be a 2 bank charger and wired to each battery or you need to switch the perko to either battery 1 or battery 2. The exception may be with some sort of combiner isolator...???

^^Richard Hangslow that is... No I wasn't trying to be one but I understand why it appears that way.

I powered through all the Tender articles as an electrical layperson after dealing with a number of differing battery issues and an explosion but cannot provide a more simplified explanation. I was merely expression caution in my comment.

I do know that the picture will charge but it is not nearly as optimal for extending the life of 2 batteries as a fully independent 2 bank system.